Nibble

In computing, a nibble, also spelled nybble to match byte, is a unit of information consisting of four bits, equivalent to one half of a byte or octet (data units of eight-bit length). The unit is alternatively called a nybl, half-byte or tetrad. In computer networking and telecommunications, the unit is also sometimes called a semi-octet, quadbit, or quartet.

A nibble uses four digits in binary positional notation (base 2) to encode one of sixteen (

2

4

{\textstyle 2^{4}}

) possible values, representing the same amount of information stored by two digits in the quaternary numeral system (base 4) or just a single hexadecimal ("hex") digit (base 16). That functional equivalence allows nibbles to typically be represented by a single hex digit, and likewise, byte values by a pair of hex digits.

Four-bit computers use nibble-sized data for storage and operations, in the form of the word unit. Such computers were used in early microprocessors, pocket calculators and pocket computers, and continue to be used in some microcontrollers. In this context, 4-bit groups were sometimes also called characters or digits rather than nibbles.

History

The term nibble originates from its representing half a byte, with byte a homophone of the English word bite. David B. Benson may have coined its use to describe four-bit values as a joke while working as a professor at Washington State University in 1958.